The present invention relates to plumbing installations, and more particularly, to dual flush systems used in gravity flush toilets and pertains particularly to an improved flush control apparatus.
For many decades household toilets have used a generally rectangular porcelain tank mounted immediately above a porcelain bowl from which about three and one-half to eight gallons of water are rapidly drained in order to flush the waste from the bowl into the sewer system. One very common design uses a flapper valve made of an elastomeric material that normally covers the drain outlet from the tank. When the flush handle on the outside of the tank is manually depressed the flapper valve is lifted and the head of water in the tank drains through the drain outlet into the bowl. The flapper valve is designed with an inverted air chamber so that it initially floats as it is lifted away from the drain outlet in the bottom of the tank. This allows sufficient flushing water to flow into the bowl even if the user immediately releases the flush handle.
A ballcock valve or toilet tank fill valve mounted in the tank is connected to a pressurized water line in the house. When the tank drains, a float ball connected to the ballcock valve descends. This turns the ballcock valve ON and it begins to refill the tank with water at a rate much slower than the rate at which water flows through the drain outlet. When the tank is nearly empty, the flapper valve closes. The tank continues to refill as the float ball connected to the ballcock rises. At the same time water from the ballcock valve enters an overflow tube and refills the bowl to the normal standing water level to provide a trap seal. Once the float ball reaches a predetermined height indicating that the tank is full, the ballcock valve completely turns OFF.
The foregoing conventional household toilet is wasteful and inefficient since a relatively large quantity of water is used to accomplish each flush. This is because the limited elevation of the tank provides only a modest water pressure head. The pressure head is obtained from the potential energy stored in the tank. As the body of water flows through the drain outlet of the tank it starts the siphoning action in the bowl and flushes the standing water in the bowl along with its waste contents into the sewer line.
Fresh water is becoming an increasingly valuable natural resource. Many geographic regions of the United States, such as Southern California, have experienced prolonged periods of drought. Arid parts of the country often take water from remote locations whose environments suffer as a result. For example, Los Angeles diverts large amounts of water from Mono Lake which has shrunk significantly since the 1930's. Furthermore, the more water that is flushed down toilets, the more volume of sewage there is that must be treated. Sewage delivery systems and treatment plants are expensive to construct and maintain. Treatment plants require large amounts of land and have offensive odors. Residents near any proposed sewage treatment site will often object vehemently.
According to a Dec. 19, 1980 report by the U. S Environmental Protection Agency (EPA), approximately 40% of the water used in a home is flushed down the toilet. The typical toilet in the U.S. uses between 3.5 and 7 gallons of water per flush. Effective Jan. 1, 1994, Federal law requires the installation of toilets in all new construction that use 1.6 gallons or less of water per flush. There is a critical need to ensure effective flushing in such toilets for sanitation reasons. Also, unless the flushing action in such low water volume toilets can be made efficient, users will flush them twice during each visit to the bathroom to ensure a complete flush, thereby negating the intended water savings.
There is also a critical need to design an apparatus to retrofit existing 3.5, 5 and 7 gallon toilets to lessen the amount of water used during each flush while maintaining an effective flush. Various approaches have been heretofore employed in regions subject to water rationing to reduce water consumption by conventional toilets. These have included lowering the tank level or introducing a brick or dam to decrease the water volume released during each flush. However, these approaches have generally been unsatisfactory because the consequent reduction in water flow into the bowl often results in incomplete flushing. Users then flush twice, compounding the waste of water.
Water shortages throughout the major portions of the United States have forced major water conservation efforts. These efforts have led to improvements in the toilet, such that as little as 1.6 gallons of water is utilized for a standard flush for solid waste removal.
Even further efforts at conservation have led to proposals for a dual flushing system, wherein a short flush is utilized to flush liquid wastes, and a long flush is utilized to flush solid wastes. The water is dispensed to the toilet bowl by way of a flush valve and seat, such as a flapper valve which allows the user to flush all or most of the tank water for a long flush, or just a portion of the tank water on the short flush. The flapper valve must be controlled to close prior to emptying the tank for the short flush. Once the toilet has been flushed, the tank is refilled automatically by a refill valve assembly connected to a water supply.
The typical flush valve assembly comprises a flapper valve having a normally downward opening air chamber which acts as a float when the flapper is raised off its seat to hold the flapper valve open when water is in the tank. This orients the air opening generally outwardly so that when the tank empties, the flapper follows the water level down to the point where the bulb and/or flange of the flapper are drawn into the flow stream which pulls the flapper down to seat, closing the flush valve. The refill mechanism is activated to refill the bowl and the tank.
Many different approaches to providing a dual flush system have been proposed. A major drawback to most of these is that they are complicated and expensive. Another drawback of many of them is that they do not function satisfactorily. One problem is that they do not account for the fact that successive short flushes typically will result in a bowl having less and less water, eventually not sealing the p-trap adequately. This invariably results in poor flush performance and failure to clear the bowl completely. It also results in wasting water by requiring double flushing to completely remove bowl contents when the trap is not fill at the start of the flush cycle.
Accordingly, it is desirable that an improved dual flush apparatus be available which is simple and effective, adequately providing for both long flushes and short flushes of a toilet, with maximum efficiency for the volume of water used.